Theoretical comparison of (111) and (100) GaAs/AlGaAs p-type quantum well infrared photodetectors

Intersubband absorptions in p-type GaAs/Al0.3Ga0.7As quantum wells (QWs) grown on (111) substrates are theoretically investigated using the multiband effective mass model. Because of the stronger band mixing of (100) QW, the peak absorption coefficient of the (100) QW is about twice as large as that of (111) QW. Nevertheless, the detectivity of (111) Quantum Well Infrared Photodetector (QWIP) is found to be similar to 30% larger than that of (100) QWIP because of the smaller dark current of (111) QWIP. This is due to the smaller heavy-hole confinement energy in (111) QW.